Most modern electronic equipment requires a power supply to provide a direct current (DC) operating potential to the electronic components contained therein. Common types of electronic equipment which use power supplies include personal computers, energy systems, telecommunication systems, audio-video equipment, consumer electronics, automotive components, and other devices which utilize integrated circuits, semiconductor chips, or otherwise require DC operating potential. Most, if not all, semiconductor components require a low voltage DC operating potential. However, many sources of electric power are alternating current (AC), or high voltage DC, which must be converted to low voltage DC for the electronic equipment.
In one common arrangement, the AC/DC power supply receives an AC input voltage, e.g., between 110 and 240 VAC, and converts the AC input voltage to the DC operating voltage. The AC voltage is routed through a full-wave rectifier bridge and filtered to produce a high voltage DC signal. The high voltage DC signal is processed through a pulse width modulated (PWM) controller and transformer assembly to generate the low voltage, regulated DC output voltage, which is used as the operating potential for the semiconductor components and other devices requiring low voltage DC supply in the electronic equipment. The low voltage DC signal is typically in the range of 1 to 12 VDC. In other cases, a DC/DC power supply receives a high voltage DC signal and provides the low voltage DC signal necessary for the electronic equipment.
Power supplies are well-known to generate heat during normal operation. The energy transfer process across the transformer as well as switching losses in the power transistor are primary sources of the heat generation in power converters. In an effort to dissipate the heat, power supply manufacturers have mechanically attached heat sinks on individual components, e.g. pressure fit metal fins on the power transistor package, and utilized cooling fans to increase air flow across the unit. The heat sink increases the surface area of the heat generating device. The cooling fan increases air flow across the surface area of the heat generating device to dissipate the heat into the surrounding air.
As electronic equipment increase in functionality, there is less room for overhead functions like power supplies. This is particular true in telecommunication systems. The original equipment manufacturers (OEMs) demand more power from dimensionally smaller power supplies, or power supplies which at least are not proportionally larger. The heat generation is one factor limiting the operational parameters and power rating which can be achieved with conventional power converters.
A need exists for a power supply having a higher power rating without increasing its feature size or ambient operating temperature.